Overload operating method for T-type 3-level converters

Abstract

The present disclosure discloses a T-shaped three-level overload operating system, including a three-level topology and an overload mode switching system. The topology is connected with a first device group and a second device group which form a T shape; the first device group is designed with an overload capacity, and the second device group is designed with a rated capacity; and the overload mode switching system is configured for being connected to the topology to control the first device group to perform overload two-level operation on the topology, or to control the second device group to perform normal three-level operation on the topology, so that the number of device groups of the overload design can be effectively reduced, and then the cost of the system can be reduced. A working method of the T-shaped three-level overload operating system is further disclosed. The topology can be rapidly switched among working modes according to an output current of the topology.

What is claimed is: 
     
       1. A T-shaped three-level overload operating system, comprising:
 an overload mode switching system; and 
 a topology, connected to a first device group and a second device group forming a T shape; 
 wherein the first device group is designed with an overload capacity, and the second device group is designed with a rated capacity; 
 the overload mode switching system is configured for being connected to the topology, so that the overload mode switching system controls, according to an output current of the topology, the first device group to perform overload two-level operation on the topology, or controls the second device group to perform normal three-level operation on the topology. 
 
     
     
       2. The T-shaped three-level overload operating system according to  claim 1 , wherein the overload mode switching system comprises:
 a current comparison module, configured for sending a level signal according to the output current of the topology; 
 a control module, configured for sending a duty cycle signal; 
 a channel calculating module, configured for receiving a level signal and the duty cycle signal, and calculating a modulation waveform comparison count value according to the received signals; 
 a pulse width modulation module, configured for generating control signals corresponding to the first device group and the second device group according to the modulation waveform comparison count value; and 
 an over-load blocking module, configured for respectively sending on-off signals to the first device group and the second device group according to the received control signals and level signal such that the first device group or the second device group switches on or switches off the topology. 
 
     
     
       3. The T-shaped three-level overload operating system according to  claim 2 , wherein the current comparison module comprises a rated current comparison module and a maximum current comparison module;
 the rated current comparison module and the maximum current comparison module are configured for outputting high-level signals or low-level signals according to the output current of the topological circuit; 
 the rated current comparison module is configured for sending the output level signal to the channel calculating module and the over-load blocking module, and the maximum current comparison module is configured for sending the output level signal to the over-load blocking module. 
 
     
     
       4. The T-shaped three-level overload operating system according to  claim 3 , wherein the channel calculating module comprises:
 a first channel selection unit, configured for receiving the level signal output by the rated current comparison module and the duty cycle signal of the control module; 
 a third calculation unit, connected to an output end of the first channel selection unit such that: when the level signal is at a low level, the third calculation unit calculates the modulation waveform comparison count value according to the received duty cycle signal; 
 a second channel selection unit, wherein an input end of the second channel selection unit is connected to an output end of the first channel selection unit; 
 a first calculation unit, connected to an output end of the second channel selection unit; and 
 a second calculation unit, connected to the output end of the second channel selection unit such that: when the level signal is at a high level, the second channel selection unit transmits the level signal to the first calculation unit or the second calculation unit respectively according to positive and negative states of the duty cycle signal, and calculates the modulation waveform comparison count value. 
 
     
     
       5. The T-shaped three-level overload operating system according to  claim 3 , wherein the over-load blocking module comprises a first AND unit group and a second AND unit group; an output end of the first AND unit group is correspondingly connected to the first device group, and an output end of the second AND unit group is correspondingly connected to the second device group; an interface of an input end of the first AND unit group receives the level signal output by the maximum current comparison module and the control signal correspondingly output by the pulse width modulation module; and an interface of an input end of the second AND unit receives the level signal output by the rated current comparison module and the control signal correspondingly output by the pulse width modulation module. 
     
     
       6. The T-shaped three-level overload operating system according to  claim 3 , wherein the T-shaped three-level overload operating system further comprises a temperature control system capable of modulating frequency, and the temperature control system capable of modulating frequency comprises:
 a temperature collection module, configured for collecting an ambient temperature and generating a temperature signal; 
 a conversion module, suitable for receiving varying temperature signals and converting the temperature signals into different triangular modulation waveform peak signals; and 
 a third channel selection unit, wherein an input end of the third channel selection unit is connected to the conversion module, and an output end of the third channel selection unit is connected to the pulse width modulation module; the third channel selection unit is configured for sending the different triangular modulation waveform peak signals to the pulse width modulation module according to the level signal of the rated current comparison module, thereby adjusting a frequency of the control signal sent by the pulse width modulation module. 
 
     
     
       7. A working method of the T-shaped three-level overload operating system, comprising the following steps:
 S 100 : sending, by the control module, value d of the duty cycle signal to the channel calculating module; 
 S 200 : detecting and making a judgment, by the current comparison module, on the output current of the topology, and sending out a judgment result in the form of a level signal; 
 S 300 : receiving, by the channel calculating module, value d of the duty cycle signal and the level signal, and calculating multiple groups of modulation waveform comparison count values corresponding to the first device group and the second device group according to the level of the level signal and positive and negative states of the duty cycle signal; 
 S 400 : sending, by the pulse width modulation module, each group of modulation waveform comparison count values to the over-load blocking module in the form of a control signal; 
 S 500 : sending, by the over-load blocking module, the on-off signals to the first device group and the second device group respectively according to the level signal and the control signal; and 
 S 600 : converting, by the conversion module, the ambient temperature collected by the temperature collection module into different triangular modulation waveform peak signals, and sending, by the third channel selection unit, different triangular modulation waveform peak signals to the pulse width modulation module according to the level signal to adjust the frequencies of the control signals; 
 wherein the first device group comprises a semiconductor device S 1  and a semiconductor device S 4 , and the second device group comprises a semiconductor device S 2  and a semiconductor device S 4 . 
 
     
     
       8. The working method of the T-shaped three-level overload operating system according to  claim 7 , wherein step S 200  comprises the following steps:
 S 210 : comparing, by the current comparison module, an output current i 0  of the topology with a rated current I rate  and a maximum current I max  respectively; 
 S 220 : outputting, by both the rated current comparison module and the maximum current comparison module, high-level signals if an absolute value of the output current i 0  is less than the rated current I rate , otherwise, executing the next step; and 
 S 230 : if an absolute value of the output current i 0  is greater than the rated current I rate  and less than the maximum current I max , outputting, by the rated current comparison module, a low-level signal, and outputting, by the maximum current comparison module, a high-level signal; otherwise, outputting, by both the rated current comparison module and the maximum current comparison module, low-level signals. 
 
     
     
       9. The working method of the T-shaped three-level overload operating system according to  claim 7 , wherein step S 300  comprises the following specific steps:
 S 310 : receiving, by the first channel selection unit, the level signal a 1  of the rated current comparison module and value d of the duty cycle signal; 
 S 320 : if the level signal a 1  is at a low level, transmitting, by the first channel selection unit, value d of the duty cycle signal to the third calculation unit, and calculating and obtaining, by the third calculation unit, the modulation waveform comparison count values CMP-13 and CMP-24, and CMP-13=CMP-24-[(1+d)/2]×C max ; if the level signal a 1  is at a high level, executing the following steps: 
 S 330 : sending, by the first channel selection unit, value d of the duty cycle signal to the second channel selection unit; 
 S 340 : if value d of the duty cycle signal is greater than or equal to 0, sending, by the second channel selection unit, value d of the duty cycle signal to the first calculation unit, and calculating and obtaining, by the first calculation unit, the modulation waveform comparison count values CMP-13=d×C max  and CMP-24=C max ; otherwise, executing the next step; and 
 S 350 : if value d of the duty cycle signal is less than 0, sending, by the second channel selection unit, value d of the duty cycle signal to the second calculation unit, and calculating and obtaining, by the second calculation unit, the modulation waveform comparison count values CMP-13=0 and CMP-24=(1+d)×C max ; 
 wherein CMP-13 represents the modulation waveform comparison count values of the semiconductor devices S 1  and S 3 ; CMP-24 represents the modulation waveform comparison count values of the semiconductor devices S 2  and S 4 ; and C max  represents a maximum triangular wave count value of the pulse width modulation module. 
 
     
     
       10. The working method of the T-shaped three-level overload operating system according to  claim 7 , wherein step S 600  comprises the following specific steps:
 S 610 : collecting, by the temperature collection module, an ambient temperature T, and sending the ambient temperature to the conversion module; 
 S 620 : converting, by the conversion module, the temperature T into a triangular wave peak value C max-T , and transmitting the triangular wave peak value C max-T  in the form of a triangular modulation waveform peak signal; 
 S 630 : receiving, by the third channel selection unit, the triangular modulation waveform peak signal and the level signal a 1  of the rated current comparison module; 
 S 640 : if the level signal a 1  is at a high level, sending, by the third channel selection unit, the triangular modulation waveform peak signal to the pulse width modulation module such that the maximum triangular wave count value C max  is a constant value C max-rate  and the pulse width modulation module works at a constant frequency; if the level signal a 1  is at a low level, executing the next step; and 
 S 650 : sending, by the third channel selection unit, the triangular wave peak signal to the pulse width modulation module such that the maximum triangular wave count value C max  is a triangular wave peak value C max-T  that changes with the temperature T, and the pulse width modulation module works at a constant frequency or variable frequencies.